Topological properties of a non-Hermitian quasi-one-dimensional chain with a flat band

We investigate the spectral properties of a non-Hermitian quasi-one-dimensional lattice in two possible dimerization configurations. Specifically, we focus on a non-Hermitian diamond chain that presents a zero-energy flat band. The flat band originates from wave interference and results in eigenstates with a finite contribution only on two sites of the unit cell. To achieve the non-Hermitian characteristics, we introduce non-reciprocal intrasite hopping terms in the chain. This leads to the accumulation of eigenstates on the boundary of the system, known as the non-Hermitian skin effect. Despite this accumulation of eigenstates, for one of the two possible configurations, we can characterize the presence of non-trivial edge states at zero energy by a real-space topological invariant known as the biorthogonal polarization. We show that this invariant, evaluated using the destructive interference method, characterizes the non-trivial phase of the non-Hermitian diamond chain. For the other possible non-Hermitian configuration, we find that there is a finite quantum metric associated with the flat band. Additionally, we observe the skin effect despite having the system a purely real or imaginary spectrum. For both configurations, we show that two non- Hermitian diamond chains can be mapped into two models of the Su-Schrieffer-Heeger chains, either non-Hermitian and Hermitian, in the presence of a flat band. This mapping allows us to draw valuable insights into the behavior and properties of these systems.Comment: 14 pages, 9 figure

Optimizing time-series forecasts for inflation and interest rates using simulation and model averaging

Motivated by economic-theory concepts – the Fisher hypothesis and the theory of the term structure – we consider a small set of simple bivariate closed-loop time-series models for the prediction of price inflation and of long- and short-term interest rates. The set includes vector autoregressions (VAR) in levels and in differences, a cointegrated VAR and a non-linear VAR with threshold cointegration based on data from Germany, Japan, UK and the US. Following a traditional comparative evaluation of predictive accuracy, we subject all structures to a mutual validation using parametric bootstrapping. Ultimately, we utilize the recently developed technique of Mallows model averaging to explore the potential of improving upon the predictions through combinations. While the simulations confirm the traded wisdom that VARs in differences optimize one-step prediction and that error correction helps at larger horizons, the model-averaging experiments point at problems in allotting an adequate penalty for the complexity of candidate models. (Author's abstract

Socioeconomic inequalities in occupational, leisure-time, and transport related physical activity among European adults: A systematic review

<p>Abstract</p> <p>Background</p> <p>This study systematically reviewed the evidence pertaining to socioeconomic inequalities in different domains of physical activity (PA) by European region.</p> <p>Methods</p> <p>Studies conducted between January 2000 and December 2010 were identified by a systematic search in Pubmed, Embase, Web of Science, Psychinfo, Sportdiscus, Sociological Abstracts, and Social Service Abstracts. English-language peer-reviewed studies undertaken in the general population of adults (18–65 years) were classified by domain of PA (total, leisure-time including sport, occupational, active transport), indicator of socioeconomic position (education, income, occupation), and European region. Distributions of reported positive, negative, and null associations were evaluated.</p> <p>Results</p> <p>A total of 131 studies met the inclusion criteria. Most studies were conducted in Scandinavia (n = 47). Leisure-time PA was the most frequently studied PA outcome (n = 112). Considerable differences in the direction of inequalities were seen for the different domains of PA. Most studies reported that those with high socioeconomic position were more physically active during leisure-time compared to those with low socioeconomic position (68% positive associations for total leisure-time PA, 76% for vigorous leisure-time PA). Occupational PA was more prevalent among the lower socioeconomic groups (63% negative associations). Socioeconomic differences in total PA and active transport PA did not show a consistent pattern (40% and 38% positive associations respectively). Some inequalities differed by European region or socioeconomic indicator, however these differences were not very pronounced.</p> <p>Conclusions</p> <p>The direction of socioeconomic inequalities in PA in Europe differed considerably by domain of PA. The contradictory results for total PA may partly be explained by contrasting socioeconomic patterns for leisure-time PA and occupational PA.</p

how many and who are affected?

Background: Nicotine dependence during adolescence increases the risk of continuing smoking into adulthood. The magnitude of nicotine dependence among adolescents in the European Union (EU) has not been established. We aimed to estimate the number of nicotine dependent 15-year-old adolescents in the EU, and identify high-risk groups. Methods: The number of nicotine dependent 15-year-olds in the EU was derived combining: (i) total number of 15-year-olds in the EU (2013 Eurostat), (ii) smoking prevalence among 15-year-olds (2013/2014 HBSC survey) and (iii) proportion of nicotine dependent 15-year-olds in six EU countries (2013 SILNE survey). Logistic regression analyses identified high-risk groups in the SILNE dataset. Results: We estimated 172 636 15-year-olds were moderately to highly nicotine dependent (3.2% of all 15 years old; 35.3% of daily smokers). In the total population, risk of nicotine dependence was higher in males, adolescents with poor academic achievement, and those with smoking parents or friends. Among daily smokers, only lower academic achievement and younger age of smoking onset were associated with nicotine dependence. Conclusion: According to our conservative estimates, more than 172 000 15-year-old EU adolescents were nicotine dependent in 2013. Prevention of smoking initiation, especially among adolescents with poor academic performance, is necessary to prevent a similar number of adolescents getting addicted to nicotine each consecutive year.publishersversionpublishe

The difference between saying and doing when it comes to training volume: Effect of motives of sport activity, age, gender and pain on training volume [Der Unterschied zwischen Sagen und Tun beim Trainingsfleiß: Effekte von Motiven sportlicher Aktivität, Alter, Geschlecht und Schmerzen auf den Trainingsumfang sportlicher Aktivitäten]

Background Health, joy/fun, body shape and society are motives for physical exercise. So far, the impact of the strength of these factors on the training scope is unclear. The study aims to analyse the association between these motives, age, gender, back pain and training volume. Materials and methods In this study, 792 participants (68% women and 32% men, mean age 53.5 years, standard deviation 11.9, range 24–85 years) were asked about their motives for physical activities, their back pain and their volume of training. Regression analyses were performed to assess the effects of the motives on training volume. Results In women, the motives joy (B$_{joy}$ = 0.23, t = 3.6, p < 0.001, r = 0.25), body shape (B$_{body shape}$ = 0.127, t = 2.0, p = 0.05, r = 0.16) and age (B$_{age}$ = 0.03, t = 2.5, p = 0.01, r = 0.17) had small (age, body shape) to medium effects (joy) on training volume. In men, only back pain had a significant positive effect (B$_{back pain}$ = 1.4, t = 4.2, p < 0.001, r = 0.35) on training volume (strong effect). Discussion and conclusion For active women, the pleasure felt during training (intrinsic motivation) and the desire for a better figure (introjected regulation = meeting external requirements) promote the amount of training. For active men, the solution to the health problem is possibly in the foreground: the greater the problem (back pain), the higher the training volume. Presumably, they have made the experience that physical training reduces back pain

Examining the Link Between Domestic Violence Victimization and Loneliness in a Dutch Community Sample: A Comparison Between Victims and Nonvictims by Type D Personality

The current study investigated whether differences in loneliness scores between individuals with a distressed personality type (type D personality) and subjects without such a personality varied by domestic violence victimization. Participants (N = 625) were recruited by random sampling from the Municipal Basic Administration of the Dutch city of ‘s-Hertogenbosch and were invited to fill out a set of questionnaires on health status. For this study, only ratings for domestic violence victimization, type D personality, feelings of loneliness, and demographics were used. Statistical analyses yielded main effects on loneliness for both type D personality and history of domestic violence victimization. Above and beyond these main effects, their interaction was significantly associated with loneliness as well. However, this result seemed to apply to emotional loneliness in particular. Findings were discussed in light of previous research and study limitations

Species-specific differences in the Pro-Ala rich region of cardiac myosin binding protein-C

Cardiac myosin binding protein-C (cMyBP-C) is an accessory protein found in the A-bands of vertebrate sarcomeres and mutations in the cMyBP-C gene are a leading cause of familial hypertrophic cardiomyopathy. The regulatory functions of cMyBP-C have been attributed to the N-terminus of the protein, which is composed of tandem immunoglobulin (Ig)-like domains (C0, C1, and C2), a region rich in proline and alanine residues (the Pro-Ala rich region) that links C0 and C1, and a unique sequence referred to as the MyBP-C motif, or M-domain, that links C1 and C2. Recombinant proteins that contain various combinations of the N-terminal domains of cMyBP-C can activate actomyosin interactions in the absence of Ca2+, but the specific sequences required for these effects differ between species; the Pro-Ala region has been implicated in human cMyBP-C whereas the C1 and M-domains appear important in mouse cMyBP-C. To investigate whether species-specific differences in sequence can account for the observed differences in function, we compared sequences of the Pro-Ala rich region in cMyBP-C isoforms from different species. Here we report that the number of proline and alanine residues in the Pro-Ala rich region varies significantly between different species and that the number correlates directly with mammalian body size and inversely with heart rate. Thus, systematic sequence differences in the Pro-Ala rich region of cMyBP-C may contribute to observed functional differences in human versus mouse cMyBP-C isoforms and suggest that the Pro-Ala region may be important in matching contractile speed to cardiac function across species

P-value based visualization of codon usage data

Two important and not yet solved problems in bacterial genome research are the identification of horizontally transferred genes and the prediction of gene expression levels. Both problems can be addressed by multivariate analysis of codon usage data. In particular dimensionality reduction methods for visualization of multivariate data have shown to be effective tools for codon usage analysis. We here propose a multidimensional scaling approach using a novel similarity measure for codon usage tables. Our probabilistic similarity measure is based on P-values derived from the well-known chi-square test for comparison of two distributions. Experimental results on four microbial genomes indicate that the new method is well-suited for the analysis of horizontal gene transfer and translational selection. As compared with the widely-used correspondence analysis, our method did not suffer from outlier sensitivity and showed a better clustering of putative alien genes in most cases